Jamar Adams Nina Brabham Anas Ghandorah Dan Holombo Materials Portland cement, lightweight aggregate, and admixtures The same type of reinforcing is used in shotcrete as in conventional concrete, like rebar, prestressed steel, and wire mesh. Additives Silica Fume- reduced permeability, increased compressive and flexural strength Air-Entraining Admixtures- improved pumpability and freeze-thaw durability Fibers- control cracking, improve impact resistance and energy absorption Accelerators- improve placement characteristics in adverse conditions and increase production capabilities Properties Hardened properties similar to conventional cast-in-place concrete Shotcrete normally has a greater compressive strength then cast in place concrete due to lower water to cement ratio Placement Uses compressive air to spray the concrete at high velocities Can be placed on soil, existing concrete, block or brick, and prefabricated forms Wet Mix- all constituents, water included, are thoroughly mixed before placement Dry Mix (Gunite)water is added to dry materials during placement Tools and Machines Concrete output: 50 yd3/hr Concrete pressure: 1361 psi Horizontal pumping distance: 1200 ft Vertical pumping distance: 450 ft Max aggregate size: 1.5 in Tools and Machines Wet Mix 2 ½ in. spray nozzle Dry Mix (Gunite) 2 in. spray nozzle Applications Homes and buildings Tunnels Channels Dams Retaining walls Bridge retrofits Recreation (pools, zoos, skateparks, waterparks) Benefits Lowers cost due to quick speed of construction Easier to construct complex forms or shapes Can use recycled materials such as fly ash and rebar in the mix Bonds well with most surfaces No forming needed, therefore lower costs References http://www.cement.org http://www.wseshotcrete.com http://www.advancedshotcrete.com http://www.gunite.us http://www.reedpumps.com http://www.earthshelter.com http://www.wsdot.wa.gov http://www.shotcretetechnologies.com